add support for the .global directive. only symbols flagged as global will be exported

This change is mostly to support code that uses the .global directive without
having to modify it first (such as commenting out those lines).

Author: wnienhaus

esp32_ulp/assemble.py

@@ -12,9 +12,10 @@
 
 
 class SymbolTable:
-    def __init__(self, symbols, bases):
+    def __init__(self, symbols, bases, globals):
         self._symbols = symbols
         self._bases = bases
+        self._globals = globals
         self._pass = None
 
     def set_pass(self, _pass):
@@ -53,7 +54,9 @@ def dump(self):
             print(symbol, entry)
 
     def export(self):
-        addrs_syms = [(self.resolve_absolute(entry), symbol) for symbol, entry in self._symbols.items()]
+        addrs_syms = [(self.resolve_absolute(entry), symbol)
+                      for symbol, entry in self._symbols.items()
+                      if symbol in self._globals]
         return sorted(addrs_syms)
 
     def to_abs_addr(self, section, offset):
@@ -93,11 +96,15 @@ def resolve_relative(self, symbol):
         from_addr = self.to_abs_addr(self._from_section, self._from_offset)
         return sym_addr - from_addr
 
+    def set_global(self, symbol):
+        self._globals[symbol] = True
+        pass
+
 
 class Assembler:
 
-    def __init__(self, symbols=None, bases=None):
-        self.symbols = SymbolTable(symbols or {}, bases or {})
+    def __init__(self, symbols=None, bases=None, globls=None):
+        self.symbols = SymbolTable(symbols or {}, bases or {}, globls or {})
         opcodes.symbols = self.symbols  # XXX dirty hack
 
     def init(self, a_pass):
@@ -236,6 +243,9 @@ def d_set(self, symbol, expr):
         value = int(expr)  # TODO: support more than just integers
         self.symbols.set_sym(symbol, ABS, None, value)
 
+    def d_global(self, symbol):
+        self.symbols.set_global(symbol)
+
     def append_data(self, wordlen, args):
         data = [int(arg).to_bytes(wordlen, 'little') for arg in args]
         self.append_section(b''.join(data))

tests/assemble.py

@@ -22,6 +22,23 @@
 """
 
 
+src_global = """\
+
+  .global counter
+counter:
+  .long 0
+
+internal:
+  .long 0
+
+  .text
+  .global entry
+entry:
+  wait 42
+  halt
+"""
+
+
 def test_parse_line():
     a = Assembler()
     lines = iter(src.splitlines())
@@ -90,8 +107,19 @@ def test_assemble_bss_with_value():
     assert raised
 
 
+def test_assemble_global():
+    a = Assembler()
+    a.assemble(src_global)
+    assert a.symbols.has_sym('counter')
+    assert a.symbols.has_sym('internal')
+    assert a.symbols.has_sym('entry')
+
+    exported_symbols = a.symbols.export()
+    assert exported_symbols == [(0, 'counter'), (2, 'entry')]  # internal not exported
+
+
 def test_symbols():
-    st = SymbolTable({}, {})
+    st = SymbolTable({}, {}, {})
     for entry in [
         ('rel_t4', REL, TEXT, 4),
         ('abs_t4', ABS, TEXT, 4),
@@ -148,4 +176,5 @@ def test_symbols():
 test_assemble()
 test_assemble_bss()
 test_assemble_bss_with_value()
+test_assemble_global()
 test_symbols()